Carbon black, used in the manufacture of tires, is an essential additive to enhance the cohesiveness of the principal ingredient of tires, rubber, and required to have a high purity of 99% or above.
The methods and apparatuses for recovering carbon black from waste tires are disclosed in Korean Utility Model No. 20-1997-0049594 (“Automatic discharging apparatus of carbon black of decomposer of scrap tires”), Korean Patent No. 0473763 (“Automatic sequential emulsification of scrap tires, carbon black, and wire core recycling apparatus”, and Korean Patent No. 0214916(“Method for preparing carbon black from scrap tires and apparatus for the same”).
However, the methods and apparatuses are all required to include a pyrolysis process for recovery of carbon black from waste tires, and the carbon black from the pyrolysis of waste tires is liable to deterioration of purity to about 78 to 82% because of the existence of other additives used in the manufacture of tires.
The reason of such deterioration in the quality of carbon black is the existence of the residual volatile substances introduced during the pyrolysis process and inorganic substances used as additives. The examples of the inorganic additives are sulfur, zinc chloride (ZnCl2), magnesium oxide (MgO), silica (SiO2), calcium carbonate (CaCO3), iron oxide (Fe2O3), and so forth. Among these inorganic additives, sulfur, in most cases, exists in the form of organic sulfur having a bonding with hydrocarbon, and desulfurization costs too much to carry out. Hence, carbon black is actually hard to be enhanced in quality through desulfurization.